Emulsions Fundamentals and Applications in the Petroleum Industry

8 Pipeline Emulsion Transportation for Heavy Oils D . P. Rimmer , A. A. Gregoli, J. A. Hamshar, and E . Yildirim Downloaded by UNIV OF ARIZONA on December 7, 2012 | http://pubs.acs.org Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

☼

Canadian Occidental Petroleum, L t d . , 1500, 635 8th Avenue, S.W., Calgary, Alberta, Canada T2P 3Z1

Oil-in-water emulsions provide a cost-effective alternative to heated pipelines or diluents for transportation of heavy crude oil or bitumen. A typical “transport emulsion” is composed of 70% crude oil, 30% aqueous phase, and 500-2000 ppm of a stabilizing surfactant formulation. The resulting emulsion has a viscosity in the 50—200-cP range at pipeline operating conditions. Nonionic surfactants have the advantage of relative insensitivity to the salt content of the aqueous phase. The ethoxylated alkylphenol family of surfactants has been used successfully for the formation of stable emulsions that resist inversion. Correlations have been developed for prediction of emulsion viscosity as a function of emulsion life and process conditions. The cost of stabilizing surfactants is estimated at $0.50 to $1.00 per barrel of crude oil for a transportation distance of200 to 400 miles.

ÏJONS OR DISPERSIONS O F HEAVY C R U D E OIL i n water o r b r i n e have b e e n u s e d i n several parts o f the w o r l d f o r p i p e l i n e transportation o f b o t h waxy a n d heavy asphaltic-type c r u d e oils. T h e h y d r o d y n a m i c a l l y s t a b i l i z e d d i s p e r sion transportation c o n c e p t is d e s c r i b e d b y the S h e l l O i l C o r p o r a t i o n c o r e f l o w t e c h n o l o g y (1). T h e use o f surfactants a n d w a t e r to f o r m o i l - i n - w a t e r emulsions w i t h c r u d e oils is t h e subject o f a l o n g series o f patents a n d was p r o p o s e d f o r use i n t r a n s p o r t i n g P r u d h o e B a y c r u d e o i l (2). F u r t h e r m o r e , surfactants m a y b e i n j e c t e d i n t o a w e l l b o r e to effect e m u l s i f i c a t i o n i n t h e p u m p o r t u b i n g f o r t h e p r o d u c t i o n o f heavy c r u d e oils as o i l - i n - w a t e r e m u l sions (3, 4). ^Corresponding author. Current address: Oxy USA, Inc., Box 3908, Tulsa OK 74102

0065-2393/92/0231-0295 $06.00/0 © 1992 American Chemical Society

In Emulsions; Schramm, L.; Advances in Chemistry; American Chemical Society: Washington, DC, 1992.

Downloaded by UNIV OF ARIZONA on December 7, 2012 | http://pubs.acs.org Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

296

EMULSIONS IN THE PETROLEUM INDUSTRY

T h e use o f o i l - i n - w a t e r e m u l s i o n s to r e d u c e the viscosity o f heavy c r u d e oils a n d b i t u m e n s a n d thus p e r m i t t h e i r transportation b y c o n v e n t i o n a l p i p e l i n e has b e e n u n d e r d e v e l o p m e n t b y C a n a d i a n O c c i d e n t a l since the f a l l o f 1984. T h e benefits o f these e m u l s i o n s m a y be a p p l i e d to p i p e l i n e trans p o r t a t i o n , to the c o m b u s t i o n o f heavy fuels, to increase the p r o d u c t i o n rates o f h e a v y - c r u d e - o i l w e l l s , a n d to i m p r o v e secondary r e c o v e r y o f heavy c r u d e o i l a n d b i t u m e n . I n this c h a p t e r , the emphasis is o n d i s c u s s i o n o f the g e n e r a l characteristics o f o i l - i n - w a t e r e m u l s i o n s as r e l a t e d to t h e i r a p p l i c a t i o n for p i p e l i n e t r a n s p o r t a t i o n . T h e i n c e n t i v e f o r d e v e l o p i n g this t e c h n o l o g y is to p r o v i d e an alternative to the use o f d i l u e n t s o r the a p p l i c a t i o n o f heat f o r viscosity r e d u c t i o n i n p i p e l i n e s f o r heavy c r u d e o i l . T h e viscosity range for o i l - i n - w a t e r e m u l s i o n s as c o m p a r e d to u n d i l u t e d heavy c r u d e oils a n d b i t u m e n s is i l l u s t r a t e d i n F i g u r e 1. A l s o i n d i c a t e d i n the figure is the viscosity specification f o r t y p i c a l p i p e l i n e s f o r heavy c r u d e o i l . A s n o t e d , the e m u l s i o n viscosity is w e l l b e l o w the r e q u i r e d l e v e l a n d p r o v i d e s o p e r a t i n g benefits c o m p a r e d to n o r m a l operations i n w h i c h viscosity r e d u c t i o n is a c h i e v e d b y use o f d i l u e n t s . T h e use o f o i l - i n - w a t e r e m u l s i o n s i n m a j o r p i p e l i n e systems represents a

100,

000

10, 000 CL

u

ω ο ω ω

1. 000 , OPERATING RANGE F O R HEAVY C R U D E OIL l

100 OIL-IN-WATER E M U L S I O N S

10

40

60

80

100

Temperature,

120

deg.

140

160

F

Figure 1. Reduction of viscosities of heavy crude oils and bitumens by conver sion to oil-in-water emulsions.



8.

RIMMERETAL.

Pipeline Emulsion Transportation for Heavy Oils

297

r a d i c a l d e p a r t u r e f r o m c o n v e n t i o n a l p r a c t i c e . A s a result, a n u m b e r o f pos sibilities are causes f o r c o n c e r n , i n c l u d i n g the p o s s i b i l i t y o f f r e e z i n g , c o r r o s i o n , e m u l s i o n separation o r i n v e r s i o n , c u s t o d y transfer, w a t e r separation, and t r e a t m e n t . S u c h issues m a y b e satisfactorily h a n d l e d a n d w i l l b e dis cussed. O i l - i r i - w a t e r e m u l s i o n s f o r p i p e l i n e t r a n s p o r t a t i o n o f heavy c r u d e oils m a y b e c o n s i d e r e d a d e v e l o p i n g t e c h n o l o g y that is not yet i n w i d e c o m m e r c i a l use. Several c o m p a n i e s have o n g o i n g p r o g r a m s i n this area a n d are c o m p e t i n g i n m a r k e t i n g o f the processes a n d the surfactant f o r m u l a t i o n s i n v o l v e d . T h e r e f o r e , m u c h o f the i n f o r m a t i o n r e l a t i n g to this t e c h n o l o g y is c o n f i d e n t i a l . I n this chapter, the t o p i c is d i s c u s s e d o n the basis o f o u r experience i n d e v e l o p m e n t a n d testing o f the e m u l s i o n transportation t e c h nology. C a n a d i a n O c c i d e n t a l ' s interest i n o i l - i n - w a t e r e m u l s i o n s is r e l a t e d to m a r k e t i n g a n d transportation o f A t h a b a s c a b i t u m e n a n d heavy A l b e r t a c r u d e oils. A laboratory a n d p i l o t - p l a n t d e v e l o p m e n t p r o g r a m was i n i t i a t e d i n late 1984 at the O c c i d e n t a l C e n t e r ( f o r m e r l y the C i t i e s Service T e c h n o l o g y C e n t e r ) i n T u l s a , O k l a h o m a . T h e p r o g r a m has i n c l u d e d the f o l l o w i n g fea tures: • d e v e l o p m e n t o f surfactant systems f o r p r e p a r a t i o n o f stable oil-in-water emulsions • e v a l u a t i o n o f e m u l s i o n p r e p a r a t i o n systems a n d selection o f optimal conditions for continuous-emulsion preparation • d e v e l o p m e n t o f laboratory tests for evaluating the stability a n d p i p e l i n i n g life o f o i l - i n - w a t e r e m u l s i o n s • c o n s t r u c t i o n o f an e m u l s i o n p i l o t p l a n t a n d testing o f the r h e o l o g i c a l p r o p e r t i e s a n d p i p e l i n e stability o f o i l - i n - w a t e r emulsions

• c o m p l e t i o n o f t w o field tests to demonstrate the t e c h n o l o g y

Process Design and Operation E m u l s i o n s d e s i g n e d f o r p i p e l i n e t r a n s p o r t a t i o n are c o m p o s e d o f a c o n t i n u ous phase c o n s i s t i n g o f w a t e r o r b r i n e , d r o p l e t s o f the heavy c r u d e o i l to b e t r a n s p o r t e d , a n d additives g e n e r a l l y c o n s i s t i n g o f c h e m i c a l surfactants. T h e p u r p o s e o f the surfactants is to p r o v i d e sufficient stability to the h y d r o c a r b o n d r o p l e t s so that they d o not coalesce o r absorb w a t e r o r b r i n e d u r i n g the p i p e l i n i n g o p e r a t i o n . T h e aqueous phase t y p i c a l l y c o m p r i s e s a p p r o x i m a t e l y 2 5 - 3 5 w t % o f the total e m u l s i o n , a n d the actual c o n c e n t r a t i o n is selected so that the m i n i m u m q u a n t i t y o f w a t e r is u s e d w h i l e m e e t i n g d e s i r e d viscosity specifications. T h e p r i n c i p a l c o m p o n e n t s o f an e m u l s i o n p i p e l i n e system are i l l u s t r a t e d i n F i g u r e 2. A s the figure indicates, the system is relatively s i m p l e In Emulsions; Schramm, L.; Advances in Chemistry; American Chemical Society: Washington, DC, 1992.

298


HEAVY CRUDE

MIXER

EMULSION STORAGE

WATER

SURFACTANT Downloaded by UNIV OF ARIZONA on December 7, 2012 | http://pubs.acs.org Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

PIPELINE SYSTEM

DRY CRUDE WATER EMULSION TREATING Figure 2. Facilities required for

a heavy-crude-oil system.

emulsion

transportation

a n d does not r e q u i r e extensive m o d i f i c a t i o n s to the p i p e l i n e system itself. T h e p r i n c i p a l steps i n c l u d e d i n o p e r a t i o n o f a transport e m u l s i o n system i n c l u d e p r e p a r a t i o n o f the o i l - i n - w a t e r e m u l s i o n , storage a n d p u m p i n g o f the e m u l s i o n , a n d finally b r e a k i n g o f the e m u l s i o n f o r r e c o v e r y o f the d r y heavy c r u d e o i l . T h e details i n v o l v e d i n each phase o f the o p e r a t i o n are d i s c u s s e d i n the f o l l o w i n g sections.

Emulsion Preparation.

P r e p a r i n g a transport e m u l s i o n is a f u n d a

m e n t a l l y s i m p l e o p e r a t i o n that i n c l u d e s the steps o f f o r m i n g a w a t e r - b r i n e s o l u t i o n o f the e m u l s i o n - s t a b i l i z i n g c o m p o s i t i o n f o l l o w e d b y a s h e a r i n g p r o cess i n w h i c h the c r u d e o i l a n d aqueous phases are m e t e r e d to a specific mixing device. E a c h d e v e l o p e r o f transport e m u l s i o n t e c h n o l o g y selects specific surfac tant f o r m u l a t i o n s f o r p a r t i c u l a r applications. T h e p r i m a r y f u n c t i o n s o f the surfactant are to r e d u c e the i n t e r f a c i a l t e n s i o n b e t w e e n the c r u d e o i l a n d aqueous phases, to p r o v i d e stability to the i n d i v i d u a l o i l droplets f o r m e d d u r i n g the s h e a r i n g process, a n d to p r e v e n t subsequent coalescence o f the d r o p l e t s . T h e surfactant m o l e c u l e s collect at the phase b o u n d a r i e s a n d p r o v i d e resistance to coalescence o f the o i l droplets b y establishing m e c h a n i c a l , steric, a n d e l e c t r i c a l barriers (5).


8.

RIMMER ET AL.


299

A w i d e range o f surfactant types m a y b e u s e d to f o r m a n d stabilize transport e m u l s i o n s . N o n i o n i c surfactants have the advantage o f relative insensitivity to the salt content o f the aqueous phase b e i n g e m p l o y e d (6). T h e g r o u p o f surfactants k n o w n as ethoxylated a l k y l p h e n o l s , r e p r e s e n t e d b y the f o r m u l a , R-C H -(CH CH -0)-H 6

4

2

2

w h e r e R c a n be any h y d r o c a r b o n a n d χ is the n u m b e r o f ethylene oxide u n i t s , is p a r t i c u l a r l y u s e f u l i n the f o r m a t i o n a n d t r a n s p o r t a t i o n o f h e a v y - c r u d e - o i l Downloaded by UNIV OF ARIZONA on December 7, 2012 | http://pubs.acs.org Publication Date: May 5, 1992 | doi: 10.1021/ba-1992-0231.ch008

emulsions. W h a t e v e r the specific f o r m u l a t i o n u s e d , the final c o n c e n t r a t i o n o f the surfactant is selected o n the basis o f the characteristics o f the h e a v y - c r u d e o i l - b r i n e system a n d the c o n d i t i o n s to w h i c h the e m u l s i o n w i l l b e subjected. T h e p r i n c i p a l factor i n f l u e n c i n g the q u a n t i t y o f surfactant r e q u i r e d is the l e n g t h o f the p i p e l i n e system i n w h i c h the e m u l s i o n w i l l be p u m p e d . T h e c o n c e n t r a t i o n o f surfactant b a s e d o n the total e m u l s i o n may range f r o m 200 to 5 0 0 0 p p m , d e p e n d i n g o n specific system characteristics. M a j o r e q u i p m e n t r e q u i r e d f o r p r e p a r a t i o n o f transport e m u l s i o n s i n cludes h e a t e d tankage f o r c r u d e o i l a n d b r i n e ; i n j e c t i o n p u m p s f o r c r u d e o i l , b r i n e , a n d surfactant; p r e m i x i n g a n d m i x i n g devices; a n d e m u l s i o n storage tanks. M i n i m a l i n s t r u m e n t a t i o n is also r e q u i r e d to m o n i t o r flow rates a n d t e m p e r a t u r e s . T h e basic m e t h o d f o r e m u l s i o n p r e p a r a t i o n is to heat the c r u d e o i l a n d b r i n e solutions to the d e s i r e d o p e r a t i n g t e m p e r a t u r e , dissolve the surfactant i n t o the b r i n e , a n d s i m u l t a n e o u s l y p u m p the c r u d e o i l a n d b r i n e t h r o u g h a m i x i n g d e v i c e i n the d e s i r e d p r o p o r t i o n s . T y p i c a l e m u l s i o n f o r m a t i o n temperatures are i n the 5 0 - 9 0 °C range. C r u d e o i l a n d b r i n e p u m p s m a y b e c e n t r i f u g a l o r positive d i s p l a c e m e n t , b u t must b e capable o f p r o v i d i n g steady flow to the m i x i n g device because e m u l s i o n p r o p e r t i e s are h i g h l y d e p e n d e n t o n the r e s u l t i n g c r u d e - o i l - b r i n e ratio. Surfactant m a y be d i s s o l v e d i n the b r i n e phase o n a b a t c h o r c o n t i n u ous basis. Static mixers p r o v i d e a s i m p l e m e t h o d for the p r e p a r a t i o n step because they r e q u i r e n o m o v i n g parts, are easy to scale u p , a n d p r o v i d e an m i x i n g intensity that is s u i t e d to p r e p a r a t i o n o f transport e m u l s i o n s . T h e t e c h n i q u e s u s e d i n the p r e p a r a t i o n o f a stable o i l - i n - w a t e r e m u l s i o n f o r p i p e l i n e transportation are i l l u s t r a t e d b y the results o f a field test i n w h i c h an A t h a b a s c a b i t u m e n was e m u l s i f i e d a n d p u m p e d t h r o u g h a 3 - i n . x 4000-ft. p i p e - l o o p system f o r a total distance o f a p p r o x i m a t e l y 500 m i l e s . T h e e m u l s i o n i n this case c o m p r i s e d 7 5 % b y w e i g h t o f the 8.3° A P I b i t u m e n a n d 2 5 % o f a synthetic b r i n e c o n t a i n i n g 1.7% N a C l . ( A P I gravity is d e f i n e d i n the Glossary.) T h e surfactant u s e d was a m i x t u r e o f t w o ethoxylated n o n y l p h e n o l surfactants; the first c o m p o n e n t c o n t a i n e d an average o f 40 ethylene oxide units p e r m o l e c u l e , a n d the s e c o n d c o m p o n e n t c o n t a i n e d 100 units. A p p r o x i m a t e l y 1500 p p m o f the surfactant m i x t u r e , b a s e d o n the total


300



e m u l s i o n , was u s e d i n p r e p a r a t i o n o f t h e e m u l s i o n . T h e e m u l s i o n was f o r m e d b y h e a t i n g b o t h t h e b r i n e a n d b i t u m e n t o 180 ° F a n d p u m p i n g t h e c o m b i n e d streams t h r o u g h a 2 - i n . static m i x e r at a rate o f about 10 ft/s. T h i s o p e r a t i o n p r o d u c e d a n e m u l s i o n w i t h a n average d r o p l e t d i a m e t e r o f 2 7 μπι a n d a viscosity near 120 c P at a m b i e n t c o n d i t i o n s . T h e e m u l s i o n was i n t r o d u c e d d i r e c t l y i n t o t h e p i p e - l o o p system f o r r h e o l o g y a n d stability testing a n d was stable t h r o u g h o u t t h e o p e r a t i n g test p e r i o d o f a p p r o x i m a t e l y 1 week. E m u l s i o n P i p e l i n e O p e r a t i o n s . P r e d i c t i o n o f p i p e l i n e pressure gradients is r e q u i r e d f o r o p e r a t i o n o f any p i p e l i n e system. Pressure g r a d i ents f o r a transport e m u l s i o n flowing i n c o m m e r c i a l - s i z e p i p e l i n e s m a y b e e s t i m a t e d v i a standard t e c h n i q u e s because c h e m i c a l l y s t a b i l i z e d e m u l s i o n s e x h i b i t r h e o l o g i c a l b e h a v i o r that is n e a r l y N e w t o n i a n . T h e e m u l s i o n viscos ity must b e k n o w n t o i m p l e m e n t these m e t h o d s . T h e best w a y t o d e t e r m i n e e m u l s i o n viscosity f o r an a p p l i c a t i o n is to p r e p a r e a n e m u l s i o n b a t c h c o n f o r m i n g to p l a n n e d specifications a n d d i r e c t l y measure t h e p i p e viscosity i n a p i p e l o o p o f at least 1-in. i n s i d e d i a m e t e r . C a r e must b e taken t o use t h e same b r i n e c o m p o s i t i o n , surfactant c o n c e n t r a t i o n , d r o p l e t size d i s t r i b u t i o n , b r i n e - c r u d e - o i l ratio, a n d t e m p e r a t u r e as are e x p e c t e d i n t h e field a p p l i c a t i o n . I n p r a c t i c e , a p i l o t - p l a n t r u n m a y not b e feasible, o r there may b e some d i s p a r i t y b e t w e e n p i p e - l o o p test c o n d i t i o n s a n d a n t i c i p a t e d c o m m e r c i a l p i p e l i n e c o n d i t i o n s . I n these cases, adjustments m a y b e a p p l i e d t o t h e best available viscosity data u s i n g adjustment factors d e s c r i b e d later t o c o m p e n sate f o r disparities i n o p e r a t i n g parameters b e t w e e n t h e m e a s u r e m e n t c o n ditions a n d t h e p i p e l i n e c o n d i t i o n s . A f t e r t h e e m u l s i o n viscosity is estimated, f r i c t i o n factor charts m a y b e u s e d d i r e c t l y t o d e t e r m i n e t h e flow r e g i m e ( l a m i n a r o r t u r b u l e n t ) a n d t h e pressure gradient. E m u l s i o n viscosity m a y b e u s e d as a n i n p u t t o a s t a n d a r d p i p e l i n e m o d e l . N e v e r t h e l e s s , i t is strongly r e c o m m e n d e d that p i l o t - p l a n t testing b e c o m p l e t e d o n n e w c r u d e oils b e f o r e c o m m e r c i a l a p p l i c a t i o n . D i r e c t m e a s u r e m e n t o f e m u l s i o n viscosity at p i p e l i n e c o n d i t i o n s is rec o m m e n d e d , especially i f l a m i n a r flow o p e r a t i o n is e x p e c t e d . V i s c o s i t y is o f lesser significance i n t u r b u l e n t flow. F o r p r a c t i c a l p u r p o s e s , e m u l s i o n viscosities m a y b e adjusted f o r v a r i a tions i n t e m p e r a t u r e , w a t e r content, a n d d r o p l e t size d i s t r i b u t i o n a c c o r d i n g to a sensitivity f o r m u l a o f t h e f o l l o w i n g t y p e : μ =

(ΎΑ¥)

WAF

2

μι

[ WAFj J

PSAF

2

i PSAFi J

(1)

w h e r e μ is e m u l s i o n viscosity (in c P ; 1 c P = 0.001 P a s ) , T A F is t h e adjusting factor f o r t e m p e r a t u r e d i f f e r e n c e , W A F is t h e adjusting factor f o r w a t e r content, P S A F is t h e adjusting factor f o r d r o p l e t size, subscript 1 refers t o c o n d i t i o n s at w h i c h viscosity is k n o w n , a n d subscript 2 refers t o c o n d i t i o n s o f


8.

RIMMERETAL.


301

a p p l i c a t i o n . T h i s f o r m u l a m a y be u s e d for field applications i n w h i c h the viscosity is k n o w n f r o m e x p e r i m e n t s , b u t it m u s t be adjusted to actual conditions. T h e adjustment factor for t e m p e r a t u r e is b a s e d o n a t e m p e r a t u r e d i f f e r ence, ( T - 2\). I f the t e m p e r a t u r e d i f f e r e n c e is negative, t h e n T A F > 1, a n d the inverse o f the T A F f r o m the correlations must be u s e d .


2

T h e t e m p e r a t u r e sensitivity o f e m u l s i o n viscosity m a y be d e s c r i b e d as a p e r c e n t a g e change i n viscosity p e r u n i t t e m p e r a t u r e change. T h e t e m p e r a t u r e - a d j u s t i n g factor varies f o r d i f f e r e n t e m u l s i o n s , d e p e n d i n g o n the base c r u d e - o i l content, b r i n e content, surfactant, a n d o t h e r variables a n d gener ally ranges f r o m about 1.8 to 3.6 cP/°C. (The v a r i a t i o n i n the viscosity o f w a t e r w i t h t e m p e r a t u r e is a p p r o x i m a t e l y 2.2 cP/°C.) T o a p p l y this factor, the percentage viscosity change must b e c o m p o u n d e d , as w i t h interest rates. F o r example, a c o r r e c t i o n o f 20 °C b a s e d o n a factor o f 2 . 5 % p e r °C w o u l d b e c a l c u l a t e d as f o l l o w s :

T A F = — L — = 0.61 1.025

(2)

20

A g e d emulsions c o n t a i n i n g a substantial p o r t i o n o f large (>200 μπι) droplets e x h i b i t a l o w e r t e m p e r a t u r e - v i s c o s i t y sensitivity, a n d this effect m u s t b e c o n s i d e r e d i n c a l c u l a t i n g pressure gradients. A d j u s t m e n t factors s h o w n are f o r t e m p e r a t u r e increases (lower viscosity). T h e inverse o f the factor applies to t e m p e r a t u r e decreases (higher viscosity). T h e viscosity o f an o i l - i n - w a t e r e m u l s i o n is sharply d e p e n d e n t o n w a t e r content. V i s c o s i t y adjustment factors f o r w a t e r content may be o b t a i n e d f r o m a c o r r e l a t i o n s u c h as that s h o w n i n F i g u r e 3. I n this figure, the adjust m e n t factor is d e f i n e d as 1.0 at the base l e v e l o f 3 0 % water. T h e actual c o r r e l a t i o n to b e u s e d is d e p e n d e n t o n the base c r u d e - o i l content a n d other factors. A p o r t i o n o f the w a t e r i n an e m u l s i o n c a n b e d i s p e r s e d w i t h i n the o i l d r o p l e t s . T h i s p o r t i o n o f the total w a t e r s h o u l d b e t r e a t e d as o i l w h e n e s t i m a t i n g e m u l s i o n viscosity. G e n e r a l l y , a d d e d w a t e r is present i n the c o n t i n u o u s phase. I f the c r u d e o i l contains w a t e r p r i o r to e m u l s i o n f o r m a t i o n , this w a t e r m a y be present i n e i t h e r the c o n t i n u o u s (water) phase o r the d i s p e r s e d (oil) phase after e m u l s i o n f o r m a t i o n , d e p e n d i n g p r i m a r i l y o n the w a t e r d r o p l e t size i n the c r u d e o i l . I n o r d e r to p r e d i c t h o w m u c h o f the w a t e r i n the c r u d e o i l w i l l b e f r e e d i n t o the c o n t i n u o u s phase, e m u l s i o n p r e p a r a t i o n experiments w i t h the actual c r u d e o i l to b e u s e d are necessary. V i s c o s i t y adjustment factors f o r d r o p l e t size d i s t r i b u t i o n m a y b e deter m i n e d b y a c o r r e l a t i o n s u c h as that s h o w n i n F i g u r e 4. M e a n d r o p l e t size is d e f i n e d o n a v o l u m e basis. D i s p e r s i t y is an i n d e x o f wideness o f the d r o p l e t size d i s t r i b u t i o n . It is d e f i n e d for this p u r p o s e as the ratio o f v o l u m e - m e a n d r o p l e t size to p o p u l a t i o n - m e a n d r o p l e t size. A s an e m u l s i o n ages, d r o p l e t coalescence occurs a n d leads to i n c r e a s e d




302

ι

• ι ι ι » • t 25 30 35 40 45 WATER CONTENT OF EMULSION, WT%

Figure 3. Viscosity adjustment factors for water content variations based on emulsions containing 30% water.

Figure 4. Viscosity adjustment factors for droplet size distribution based on viscosity at 30-^m mean droplet size and dispersity of 3.0.


8.

RIMMERETAL.


303

d r o p l e t size a n d dispersity. T h e s e increases, i n t u r n , cause r e d u c e d e m u l s i o n viscosity. E m u l s i o n viscosity m a y be r e l a t e d d i r e c t l y to a g i n g b y an e q u a t i o n o f the f o r m : μ = μ exp (-fc0)


0

(3)

w h e r e μ is the viscosity (subscript 0 indicates i n i t i a l viscosity), θ is the t i m e o f e m u l s i o n transport, a n d k is a constant c h a r a c t e r i z i n g the e m u l s i o n d e g r a d a t i o n rate. T h i s e q u a t i o n c a n also b e w r i t t e n i n terms o f distance t r a v e l e d rather t h a n t i m e o f transport. T h e value o f k m a y be m e a s u r e d e x p e r i m e n t a l l y f o r a g i v e n e m u l s i o n . T h e e m u l s i o n d e g r a d a t i o n rate decreases as p i p e d i a m e t e r increases. A conservative a s s u m p t i o n f o r c a l c u l a t i o n o f viscosities f o r p i p e l i n e d e s i g n is that the d e g r a d a t i o n rate is p r o p o r t i o n a l to the s u r f a c e - t o - v o l u m e ratio (1/d), w h e r e d is the p i p e d i a m e t e r . E m u l s i o n aging rates increase w i t h t e m p e r a t u r e . A g i n g rates i n t u r b u lent flow appear to b e c o m e arrested after a c e r t a i n p o i n t , generally b e i n g less t h a n the rates o b s e r v e d i n l a m i n a r flow. A g i n g rates are s u p p r e s s e d b y i n c r e a s e d surfactant c o n c e n t r a t i o n as a result o f the anticoalescence action o f the surfactant. T h e viscosity o f an o i l - i n - w a t e r e m u l s i o n generally varies i n p r o p o r t i o n to the c o n t i n u o u s - p h a s e viscosity. I f c o n c e n t r a t e d b r i n e s or b r i n e s c o n t a i n i n g additives are to b e u s e d , t h e n the c o n t i n u o u s - p h a s e viscosity m a y b e substantially greater t h a n that o f water, a n d a c o r r e c t i o n s h o u l d be a p p l i e d . Specific adjustment factors f o r this effect m a y be e s t i m a t e d as the ratio o f viscosities o f the b r i n e s i n the k n o w n a n d u n k n o w n e m u l s i o n s . T h e surfactant c o n c e n t r a t i o n is n o r m a l l y not h i g h e n o u g h to substan tially affect the c o n t i n u o u s - p h a s e viscosity. H o w e v e r , changes i n surfactant c o n c e n t r a t i o n f o r a p i p e l i n e a p p l i c a t i o n generally cause an i n d i r e c t effect o n r h e o l o g y b y w a y o f t h e i r effects o n e m u l s i o n p r e p a r a t i o n a n d o n the e m u l sion aging rate. G e n e r a l l y , an increase i n surfactant c o n c e n t r a t i o n results i n a s m a l l e r i n i t i a l d r o p l e t size a n d s l o w e r e m u l s i o n aging. B o t h o f these c o n d i tions t e n d to increase viscosity.

Monitoring Emulsion Aging. T h e surfactants u s e d i n transport e m u l s i o n s may g r a d u a l l y lose t h e i r a b i l i t y to stabilize the o i l d r o p l e t s . A s the o i l droplets coalesce, a two-phase m i x t u r e is f o r m e d , a n d it r e m a i n s p u m p a b l e w i t h no significant change i n effective viscosity. T h i s process is r e f e r r e d to as e m u l s i o n f a i l u r e . A n alternative to this process is i n v e r s i o n o f the e m u l s i o n , i n w h i c h a w a t e r - i n - o i l e m u l s i o n is f o r m e d w i t h a p o t e n t i a l l y v e r y h i g h viscosity. P r o p e r s e l e c t i o n o f the surfactant f o r m u l a t i o n c a n p r e vent the o c c u r r e n c e o f e m u l s i o n i n v e r s i o n . Indicators o f e m u l s i o n aging that may be m o n i t o r e d i n c l u d e d r o p l e t size g r o w t h , viscosity d e c l i n e , surfactant loss, a n d r e d u c t i o n o f shear stability.


304


D r o p l e t g r o w t h rates a n d viscosity d e c l i n e rates b o t h are e x p o n e n t i a l p r o cesses, f o l l o w i n g a straight l i n e o n a s e m i - l o g p l o t (log μ o r l o g d vs. t i m e ) , w h e r e d is the m e a n d r o p l e t d i a m e t e r . E m u l s i o n failure is also associated w i t h a c e r t a i n m i n i m u m viscosity, d e p e n d i n g o n w a t e r content, c r u d e - o i l content, t e m p e r a t u r e , etc. V i s c o s i t y a n d m e a n d r o p l e t size may be p r o j e c t e d to estimate the t i m e r e m a i n i n g b e f o r e e m u l s i o n f a i l u r e . T h e u l t i m a t e d r o p p


?

let size a n d viscosity s h o u l d be d e t e r m i n e d e x p e r i m e n t a l l y f o r the same formulation i n a pilot-plant pipe loop. T h e e m u l s i o n surfactant c o n c e n t r a t i o n generally declines g r a d u a l l y as the e m u l s i o n approaches f a i l u r e , c u l m i n a t i n g i n a s u d d e n sharp d r o p at o r after the t i m e o f e m u l s i o n f a i l u r e . C h a n g e s o f surfactant c o n c e n t r a t i o n t e n d to lag b e h i n d changes evident f r o m d r o p l e t size a n d o t h e r indicators, a n d this situation makes surfactant c o n c e n t r a t i o n analysis ineffective as an i n d i cator o f a p p r o a c h i n g e m u l s i o n f a i l u r e . E m u l s i o n l i f e expectancy f o r a f o r m u l a t i o n may be conservatively scaled u p f r o m 2 - i n . p i p e - l o o p tests at the same v e l o c i t y b y d e m o n s t r a t i n g that the e m u l s i o n w i l l survive transport f o r the d e s i r e d actual distance i n the p i l o t p l a n t . P i l o t - p l a n t transport is a m o r e severe test o f e m u l s i o n life than trans p o r t i n larger lines. T h e conservative nature o f this scale-up c r i t e r i o n tends to dictate specification o f some excess surfactant f o r a large-scale a p p l i c a t i o n b e y o n d the m i n i m u m q u a n t i t y r e q u i r e d .

Effects of Pumps and Valves.

T h e flow o f emulsions

through

p i p e l i n e p u m p a n d valves c o u l d p o t e n t i a l l y affect the e m u l s i o n p r o p e r t i e s . Pumps. I m p e l l e r t i p s p e e d is a u s e f u l g u i d e to relate c e n t r i f u g a l p u m p s i n terms o f the energy they may i m p a r t o n an e m u l s i o n . Several p u m p s have b e e n tested o n e m u l s i o n service w i t h t i p speeds u p to 200 ft/s, c o m p a r e d to t y p i c a l p u m p - s t a t i o n applications o f approximately 300 ft/s. T h e results o f these tests show that e m u l s i o n shear stability is u n c h a n g e d after several passes t h r o u g h a c e n t r i f u g a l p u m p , t y p i c a l o f multistage p u m p station a p p l i c a t i o n . S o m e u n d e r s i z e d m a t e r i a l is f o r m e d at the expense o f o v e r s i z e d . T h e s e results i n d i c a t e that c o m m e r c i a l p u m p applications s h o u l d not b e a p r o b l e m . T e s t i n g has b e e n l i m i t e d , h o w e v e r , a n d thus p r i o r to any c o m m e r c i a l a p p l i c a t i o n , the specific p u m p characteristics s h o u l d be c o m p a r e d against the p u m p s already tested. P u m p tip speeds a n d the p u m p m o d e l i n g l a w that relates p u m p geometries s h o u l d be r e v i e w e d . Passage o f e m u l s i o n t h r o u g h a c e n t r i f u g a l p u m p at a b n o r m a l l y l o w rates a n d at a h i g h b a c k pressure can shorten the e m u l s i o n shear stability. G e a r p u m p s are low-shear devices a n d d o not adversely affect the e m u l s i o n . Valves. L i m i t e d laboratory testing shows that emulsions can be let d o w n across a pressure d i f f e r e n t i a l o f 1000 ψ (6895 k P a ) , t y p i c a l o f c o m m e r -


8.

RIMMERETAL.


305

c i a l applications, w i t h m a r g i n a l r e d u c t i o n i n shear stability. V e l o c i t i e s across the valve p o r t r e a c h e d 130 ft/s (39.6 m/s).


Effects of Pipeline Shutdown and Restart. W h e n a p i p e l i n e c o n t a i n i n g e m u l s i o n is s t o p p e d a n d a l l o w e d to r e m a i n s h u t - i n for one o r m o r e days, t h e r e is generally a h i g h e r than n o r m a l pressure gradient o n restarting flow. I n p i l o t - p l a n t experiments, the pressure gradient substan tially r e t u r n e d to its n o r m a l value w i t h i n 5 m i n . T h e i n c r e a s e d pressure gradient is d u e to c r e a m i n g o r stratification o f the e m u l s i o n . A d d i t i o n a l energy is r e q u i r e d o n restart to redisperse the m a t e r i a l u n i f o r m l y . R e s t a r t i n g o f a phase-separated m i x t u r e (failed e m u l s i o n ) is s i m i l a r to restarting an e m u l s i o n , b u t the starting pressure surge is substantially greater as a result o f total separation o f phases.

Fluid Reing Restarted

Pressure Surge Range, Percent of Steady-State Pressure

Emulsion (30% water) Emulsion (38% water) Phase-separated mixture (30%)

100-250, 200 typical 100-150, 130 typical 400-800, 700 typical

Corrosion Considerations. C o r r o s i o n rates are d i c t a t e d b y the p r o p e r t i e s o f the b r i n e b e i n g u s e d . P i l o t - p l a n t testing w i t h an e l e c t r o c h e m i cal c o r r o s i o n rate p r o b e i n d i c a t e d c o r r o s i o n rates o f less t h a n 5 mils/year f o r e m u l s i o n s flowing i n p i p e s . T h e c o r r o s i o n rate d e c l i n e d over t i m e , p r e s u m ably because o f f o r m a t i o n o f an o i l layer o n the m e t a l . I n a l l p i l o t a n d field tests that w e c o n d u c t e d , p i p e walls have always s h o w n a t h i n (approximately 0.001-in.) layer o f c r u d e o i l o n the w a l l after e m u l s i o n r u n s . C o r r o s i o n rates for live b r i n e s c o n t a i n i n g C 0 o r H S are expected to b e h i g h e r t h a n those m e a s u r e d o n d e a d brines i n p i l o t - p l a n t testing. O n - l i n e c o r r o s i o n m o n i t o r i n g i n the field is i n d i c a t e d o n a case-by-case basis. C o r r o s i o n rates for e m u l s i o n s are not expected to b e any w o r s e t h a n those f o r c r u d e oils c o n t a i n i n g b r i n e . 2

2

Demulsification. T h e final part o f the e m u l s i o n transportation sys t e m is d e m u l s i f i c a t i o n o r b r e a k i n g o f the o i l - i n - w a t e r e m u l s i o n to r e c o v e r dry c r u d e o i l . T h e e q u i p m e n t a n d process c o n d i t i o n s r e q u i r e d f o r this o p e r a t i o n are the same or s i m i l a r to those u s e d for a c o n v e n t i o n a l c r u d e - o i l d e w a t e r i n g process. T h e t e c h n i q u e s u s e d f o r d e m u l s i f i c a t i o n o f a transport e m u l s i o n may i n c l u d e r a i s i n g the t e m p e r a t u r e o f the e m u l s i o n , a d d i t i o n o f e m u l s i o n b r e a k i n g additives, a d d i t i o n o f diluents to r e d u c e the viscosity o f the heavy c r u d e o i l , a n d the use o f e q u i p m e n t d e s i g n e d to p r o m o t e coalescence o f the c r u d e - o i l d r o p l e t s . R a i s i n g the t e m p e r a t u r e o f the e m u l s i o n increases the



306


d i f f e r e n c e i n d e n s i t y b e t w e e n the h y d r o c a r b o n a n d aqueous phases a n d encourages c r e a m i n g o f the e m u l s i o n . T h e r e d u c e d viscosity o f the h y d r o c a r b o n phase at h i g h t e m p e r a t u r e s also i m p r o v e s the o p e r a b i l i t y o f the d e m u l s i f i c a t i o n process. T h e viscosity o f the c r u d e o i l m a y also b e r e d u c e d b y a d d i t i o n o f d i l u e n t s i f this o p e r a t i o n is a p p r o p r i a t e f o r d o w n s t r e a m p r o cessing. T h e use o f d e m u l s i f y i n g additives is d e s i g n e d to counteract the effects o f the e m u l s i f y i n g surfactants. T h e surfactants u s e d i n the s t a b i l i z a t i o n o f e m u l s i o n s o f heavy c r u d e oils generally have a h i g h H L B ( h y d r o p h i l i c - l i p o p h i l i c balance). F o r d e m u l s i f i c a t i o n operations, the effectiveness o f these surfactants m a y be c o u n t e r a c t e d b y a d d i t i o n o f surfactants w i t h a l o w H L B . M a n y c o m m e r c i a l l y available p r o d u c t s w i t h p r o p r i e t a r y c o m p o sitions are available f o r this p u r p o s e . E t h o x y l a t e d a l k y l p h e n o l s , w h i c h are u s e d i n the e m u l s i f i c a t i o n process, m a y also be u s e d f o r d e m u l s i f i c a t i o n i f c o m p o n e n t s are selected w i t h a l o w n u m b e r o f ethylene oxide groups. T h e basic p r o c e d u r e f o r d e m u l s i f i c a t i o n o f a h e a v y - c r u d e - o i l transport e m u l s i o n t h e n consists o f the f o l l o w i n g steps: 1. Raise the e m u l s i o n t e m p e r a t u r e to 190 to 250 °F. 2. A d d d e m u l s i f i c a t i o n surfactants. 3. P o s s i b l y a d d d i l u e n t s f o r viscosity r e d u c t i o n . 4. P r o v i d e residence t i m e sufficient f o r separation o f the o i l a n d w a t e r phases. T h e t i m e r e q u i r e d f o r separation i n step 4 d e p e n d s o n the density d i f f e r e n c e b e t w e e n the o i l a n d w a t e r phases, the t r e a t i n g e q u i p m e n t , a n d the t r e a t i n g temperature. I n some cases it may b e desirable to p e r f o r m the d e m u l s i f i c a t i o n process i n t w o stages. I n the first stage the b u l k o f the water m a y be r e m o v e d at a m i n i m u m process severity, as already d e s c r i b e d . A s e c o n d process stage at a h i g h e r t e m p e r a t u r e a n d p o s s i b l y at elevated pressure may t h e n be u s e d for final d r y c r u d e - o i l recovery. C h a n g e s i n process c o n t r o l p r o c e d u r e s f o r the d e m u l s i f i c a t i o n o p e r a t i o n m a y be r e q u i r e d for o i l - i n - w a t e r e m u l s i o n s . Interface d e t e c t i o n i n s t r u ments must b e able to detect the d i f f e r e n c e i n w a t e r a n d an o i l - i n - w a t e r e m u l s i o n . A d j u s t m e n t o f c o n t r o l levels i n separation vessels may b e r e q u i r e d for proper operation. I n some cases, m i n i m a l effort is r e q u i r e d for the d e m u l s i f i c a t i o n p r o cess. F o r example, i n field tests, adequate separation o f a b i t u m e n e m u l s i o n c o u l d b e a c h i e v e d w i t h o u t the use o f d e m u l s i f i e r s b y r a i s i n g the t e m p e r a t u r e o f the e m u l s i o n to 190 °F a n d p r o v i d i n g 24 to 48 h o f r e s i d e n c e t i m e i n q u i e s c e n t storage tanks. H o w e v e r , p r o p e r s e l e c t i o n o f d e m u l s i f i c a t i o n c h e m i c a l s is essential w h e n t r e a t i n g the e m u l s i o n s i n c o n v e n t i o n a l e q u i p m e n t o n a c o n t i n u o u s - f l o w basis.


8.

RIMMERETAL.


307


T h e w a t e r separated i n the d e m u l s i f i c a t i o n step is s i m i l a r i n character to w a t e r p r o d u c e d i n a c o n v e n t i o n a l refinery d e s a l t i n g process. A l t h o u g h n o d e t r i m e n t a l effects are a n t i c i p a t e d , the impacts o f surfactants i n the w a t e r o r d o w n s t r e a m p r o c e s s i n g units m u s t b e evaluated f o r each specific case. T h e w a t e r phase may c o n t a i n surfactant fragments that c o u l d r e q u i r e t r e a t m e n t o r r e m o v a l p r i o r to d i s p o s a l . R e f i n e r i e s , h o w e v e r , use a variety o f c h e m i c a l s , catalysts, additives, etc., m a n y o f w h i c h e n d u p i n waste streams a n d r e q u i r e treatment.

Storage, Maintenance, and Special Requirements. I f o i l - i n w a t e r e m u l s i o n s m u s t b e s t o r e d i n tanks e i t h e r b e f o r e o r after p i p e l i n i n g , agitation is r e q u i r e d to p r e v e n t c r e a m i n g i n the tank. C r e a m i n g refers to the c o n c e n t r a t i o n o f o i l droplets o n the surface o f the fluid that c a n result i n a t h i c k s k i n o r crust that may not r e a d i l y b e d i s p e r s e d i n t o the b u l k o f the e m u l s i o n . S l o w agitation just sufficient to c o n t i n u a l l y r o l l the tank contents w i l l p r e v e n t c r e a m i n g . Excessive agitation s h o u l d be a v o i d e d to p r e v e n t shear d e g r a d a t i o n o f the e m u l s i o n . M a i n t e n a n c e r e q u i r e m e n t s s h o u l d be the same f o r an e m u l s i o n p i p e l i n e as f o r a c o n v e n t i o n a l p e t r o l e u m p i p e l i n e . S i m i l a r l y , n o u n u s u a l m a i n t e n a n c e is e x p e c t e d for the e m u l s i o n p r e p a r a t i o n o r d e m u l s i f i c a t i o n parts o f the system. I f the p i p e l i n e u s e d f o r e m u l s i o n t r a n s p o r t a t i o n is a c o m m o n c a r r i e r , special p r o c e d u r e s may be necessary for m e t e r i n g a n d custody transfer. O n l i n e i n s t r u m e n t s f o r m e a s u r e m e n t o f e m u l s i o n w a t e r content m a y b e re q u i r e d i n s u c h an a p p l i c a t i o n .

Economics T h e e c o n o m i c analysis o f an e m u l s i o n p i p e l i n e transportation system is h i g h l y site specific a n d d e p e n d s o n several factors that cannot be s p e c i f i e d f o r a g e n e r a l case. H o w e v e r , e x a m p l e cases are p r e s e n t e d to illustrate t y p i c a l costs associated w i t h use o f the technology.

Surfactant Cost. A m a j o r cost associated w i t h u s i n g o i l - i n - w a t e r e m u l s i o n s is the cost o f the surfactants u s e d to stabilize the o i l d r o p l e t s w i t h i n the e m u l s i o n . T h i s cost w i l l d e p e n d u p o n the surfactant f o r m u l a t i o n c h o s e n f o r the specific a p p l i c a t i o n , the transportation distance i n v o l v e d , a n d i n s o m e cases the type o f c r u d e o i l b e i n g e m u l s i f i e d . O n the basis o f the f o r m u l a t i o n that w e t y p i c a l l y use a n d c u r r e n t m a r k e t p r i c e s , the e s t i m a t e d surfactant cost to transport heavy c r u d e o i l as an e m u l s i o n f o r a distance o f 200 to 400 miles (322 to 644 k m ) is a p p r o x i m a t e l y $0.50 to $1.00 p e r b a r r e l o f c r u d e o i l s h i p p e d . F o r greater p i p e l i n e lengths, u p to 1500 to 2000 m i l e s , the surfactant cost m a y increase b y 5 0 - 1 0 0 % relative to the shorter d i s -


308



tances. T h e s e costs are b a s e d o n conservative estimates o f the quantities o f surfactants r e q u i r e d a n d m a y l i k e l y be r e d u c e d after o p t i m i z a t i o n f o r a particular application.

Emulsion Transportation versus Diluent Recycle. T h e p r e v a i l i n g m e t h o d i n use f o r t r a n s p o r t a t i o n o f heavy c r u d e o i l a n d b i t u m e n i n A l b e r t a is to d i l u t e the c r u d e o i l w i t h a p p r o x i m a t e l y one part o f a l i g h t h y d r o c a r b o n d i l u e n t , t y p i c a l l y n a t u r a l gas condensate, to t w o parts o f c r u d e o i l . T h i s q u a n t i t y o f d i l u e n t is generally sufficient to r e d u c e the c r u d e - o i l viscosity e n o u g h so that m i n i m u m p i p e l i n e specifications m a y be met. H o w ever, a p o t e n t i a l shortage o f condensate d i l u e n t m a y l i m i t the use o f this m e t h o d for h e a v y - c r u d e - o i l transportation. A n alternative to the o n c e t h r o u g h use o f d i l u e n t is to r e c o v e r the d i l u e n t at the p i p e l i n e e n d b y f r a c t i o n a t i o n a n d recycle it to the start o f the p i p e l i n e . T h i s m e t h o d is c o m p a r e d i n the f o l l o w i n g section w i t h the use o f o i l - i n - w a t e r e m u l s i o n s for the same h y p o t h e t i c a l a p p l i c a t i o n . T h e basis f o r this example is a 2 4 - i n . , 200m i l e p i p e l i n e d e s i g n e d to transport 300,000 barrels p e r day o f b l e n d o r 200,000 barrels p e r day o f u n d i l u t e d heavy c r u d e o i l . A p a r a l l e l l i n e is assumed f o r r e t u r n o f separated d i l u e n t . O t h e r bases a n d assumptions u s e d i n the evaluation are as f o l l o w s : Emulsion properties Gravity Viscosity Crude-oil concentration Flow rate Surfactant cost Water-disposal cost Tariffs F o r blend F o r diluent F o r emulsion Fuel Electricity Capital related costs

10° A P I (sp. gr. = 1) 100 cP 70% 286,000 barrels per day (45,474 m /day) $0.75 per barrel of crude oil $0.20 per barrel of water 3

$1.00 per barrel $0.50 per barrel $0.50 per barrel $5.00 per million Btu $0.06 per kilowatt hour 25% of total installed cost

T h e r e d u c e d tariffs for e m u l s i o n s c o m p a r e d to b l e n d are a s s u m e d b e cause o f the 7 5 % r e d u c t i o n i n viscosity f o r emulsions versus b l e n d a n d the resultant decrease i n p u m p i n g costs. T h e c a l c u l a t e d c r u d e - o i l transportation cost f o r the e m u l s i o n case was b a s e d o n estimates o f the r e q u i r e d c a p i t a l investments f o r e m u l s i f i c a t i o n a n d o i l r e c o v e r y facilities, o p e r a t i n g costs i n c l u d i n g p i p e l i n e tariffs, surfac tant costs, a n d w a t e r disposal. T h e costs f o r the recycle b l e n d case i n c l u d e d the n o r m a l p i p e l i n e o p e r a t i n g costs p l u s the costs o f separating a n d p u m p i n g the d i l u e n t back to the start o f the p i p e l i n e . T h e costs assumed for the


8.

RIMMERETAL.

309


e m u l s i o n ease w e r e based o n the a s s u m p t i o n that the costs o f c r u d e - o i l p r o d u c t i o n facilities w i l l not be i n f l u e n c e d b y the subsequent c o n v e r s i o n o f the p r o d u c e d c r u d e o i l to an o i l - i n - w a t e r e m u l s i o n . I n some cases, these costs m a y be r e d u c e d b y r e d u c i n g the n o r m a l c r u d e - o i l d e w a t e r i n g r e q u i r e ments necessary to m e e t u s u a l p i p e l i n e specifications (

Emulsions Fundamentals and Applications in the Petroleum Industry

Recommend Documents